I'm pretty sure people are right when they say that dark dude on the horse was Odin but a few doubts cross my mind. Odin's horse had 6 legs in every other incarnation, Usually portrayed in white armor (and white horse), no other primals were shown during the last part, Could be a Garlean? The only thing's that make me think it is Odin is this is the first Horse mounted badguy(?), and the silhouette with the moon.